1. Field of the Invention
The invention concerns a device and a process for controlling a thick matter pump with two conveyor cylinders communicating via end openings in a material supply container, operable in counter stroke by hydraulic drive cylinders controlled by a hydraulic reversible pump, with a hydraulic actuated pipe switch provided within the material supply container, of which the inlet side is alternatingly connectible to one of the openings of the conveyor cylinders leaving open the respective other opening and on the outlet side is connected with a conveyor line, wherein the drive cylinders are respectively connected at their one end via a hydraulic line with a connection of the reversible pump and on their other end are hydraulically connected with each other via an oscillating oil line, and with a device for reversing the reversible pump and the pipe switch after completion of each piston stroke.
2. Related Art of the Invention
A device for control of a two cylinder thick matter pump of this type is known (DE 195 42 258), in which the end position of the piston of the drive cylinder can be determined by means of cylinder switch sensors for producing end position signals. The reversal of the flow-through of the reversible pumps is there initiated by the end position signal of the drive cylinder. At the same time the pipe switch is reversed. This type of pump control functions reliably, when the drive cylinder on the one hand and the drive cylinder of the pipe switch on the other hand are provided in two hydraulic circuits, when for example the pipe switch is controllable via a pressure accumulator charged by the hydraulic pump separate from the hydraulic circuit of the drive cylinder. In the so-called single circuit pumps, in which the pressure fluids for the reversing of the pipe switch are branched off directly from the hydraulic circuit of the drive cylinders supplied by the reversible pump, there may result, above all in the case of variations of the conveyed amounts and the consistency of the conveyed material, interruptions or interference when the pistons have not reached their end position and the reversing of the pipe switch already is initiated. Added to this is that the pipe switch movement in this case is carried out without shock damping, and banging and bottoming-out noises occur when the piston impacts the cylinder end.